Currently, the assay to measure immunogenicity of a flu vaccine are serologically based hemagglutinin inhibition and microneutralization assays. The assay results vary from inter and intra laboratories making it difficult to compare results across multiple sites. The assay under development in this IAA will allow for quantitation of results which could be compared across multiple sites using standardized reagents and could have regulatory impact since results from clinical trials evaluating different vaccine candidates can be compared globally.